The invention relates generally to chemical sensors. In particular, relates to chemical sensors that employ an annular photonic crystal fiber coupled to an illumination source at one end to transmit an emission pattern transverse to the fiber's outer surface for comparison against an established pattern to detect the presence of a signature material.
The United States faces various technical challenges to national security, including threats from chemical and biological warfare (CBW) agents, as well as detection of toxic industrial chemical (TIC) materials. Depending on the technology used, conventional CBW detectors are capable of identifying and/or detecting between eight and twenty different agents, with verification and validation of field results usually requiring approximately forty-eight hours. The most accurate identification of about twenty chemicals including most chemical warfare agents and some volatile organic compound (VOC) molecules is conventionally performed, in the field and in the laboratory, by gas-chronomatography-mass-spectrometry (GCMS).
Both commercial enterprises and military organizations desire a detector capable of identifying known and novel CBW and TIC agents to defend both war-fighters and civilians. Some CBW agents are very deadly to large numbers of people. For example in 1984, exposure to concentrations of forty metric tons of methyl-isocyanate over an area of several hundred square miles in Bhopal, India in 1984, killed about thirty-eight-hundred people with economic loss of several hundred million dollars.